<template>
  <div class="score-case">
    <div class="table">
      <table>
        <thead>
          <tr>
            <th>编号</th>
            <th>科目</th>
            <th>成绩</th>
            <th>考试时间</th>
            <th>操作</th>
          </tr>
        </thead>
        <tbody>
          <tr v-for="(item,index) in list" :key="item.id">
            <td>{{index+1}}</td>
            <td>{{item.subject}}</td>
            <td :class="{red :item.score<60}">{{item.score}}</td> 
            <td>{{formatDate(item.date)}} (中国标准时间)</td>
            <td><a href="#" @click.prevent="delFn(id)">删除</a></td>
          </tr>
          <!-- <tr >
            <td>2</td>
            <td>数学</td>
            <td>100</td>
            <td>Tue Jun 07 2022 10:00:00 GMT+0800 (中国标准时间)</td>
            <td><a href="#">删除</a></td>
          </tr> -->
        </tbody>
        <tbody v-show='list.length==0'>
          <tr>
            <td colspan="5">
              <span class="none">暂无数据</span>
            </td>
          </tr>
        </tbody>
        <tfoot v-show='list.length'>
          <tr >
            <td colspan="5">
              <span>总分：{{scoreSum}}</span>
            <span style="margin-left:50px">平均分：{{averSum}}</span>
            </td>
          </tr>
        </tfoot>
      </table>
    </div>
    <div class="form">
      <div class="form-item">
        <div class="label">科目：</div>
        <div class="input">
          <input type="text" v-model.trim="subject" placeholder="请输入科目" />
        </div>
      </div>
      <div class="form-item">
        <div class="label">分数：</div>
        <div class="input">
          <input type="text" v-model.number="score" placeholder="请输入分数" />
        </div>
      </div>
      <div class="form-item">
        <div class="label"></div>
        <div class="input">
          <button class="submit" @click="addFn">添加</button>
        </div>
      </div>
    </div>
  </div>
</template>

<script>
import moment from 'moment'
export default {
  name: 'ScoreCase',
  data () {
    return {
      list:JSON.parse(localStorage.getItem('case')) || [],//获取本地数据，如果前面的为假，就为[]
      subject: '',
      score: ''
    }
  },
  methods:{
    formatDate(dt){
      return moment(dt).format("YYYY-MM-DD HH:mm:ss")//引入moment改时间格式
    },
    delFn(id){
      //根据索引找id
      const index=this.list.findIndex(item=>item.id==id)
      this.list.splice(index,1)//删除
      // 或者通过filter筛选出符合的
      // this.list=this.list.filter(item=>item.id!==id)
      //筛选出符合的id，符合的删掉
    },
    addFn(){
      //添加
      if(this.score>=0 && this.score<=100 && this.subject && this.score){
        this.list.push({
          // list里面有元素，有就用最后一位元素的id+1
          // 没有的话就让这个元素的id为1
          id:this.list.length?this.list.at(-1).id+1 :1, //at(-1)表示最后一项
          score :this.score,
          subject :this.subject,
          date:new Date()
        })
        this.subject = ''
        this.score =''  //添加成功后归零
      }else{
        alert('你输入的有问题撒')//输入有误弹出
      }
    }
  },
  computed :{
    // 求和
    scoreSum(){
      return this.list.reduce((sum,item)=>sum+item.score,0)//初始值为0
    },
    //求平均值
    averSum(){
return this.list.length?(this.scoreSum/this.list.length).toFixed(2):0//保留两位小数
//如果有数据则求平均值，数据删完了为0
    }
  },
  watch:{
    list:{
      deep:true, //深度监听
      handler(){//数据发生变化，
        localStorage.setItem( 'case',JSON.stringify(this.list))//本地存储
      }
    }
  }
};
</script>

<style lang="less">
.score-case {
  width: 1000px;
  margin: 50px auto;
  display: flex;
  .table {
    flex: 4;
    table {
      width: 100%;
      border-spacing: 0;
      border-top: 1px solid #ccc;
      border-left: 1px solid #ccc;
      th {
        background: #f5f5f5;
      }
      tr:hover td {
        background: #f5f5f5;
      }
      td,
      th {
        border-bottom: 1px solid #ccc;
        border-right: 1px solid #ccc;
        text-align: center;
        padding: 10px;
        &.red {
          color: red;
        }
      }
    }
    .none {
      height: 100px;
      line-height: 100px;
      color: #999;
    }
  }
  .form {
    flex: 1;
    padding: 20px;
    .form-item {
      display: flex;
      margin-bottom: 20px;
      align-items: center;
    }
    .form-item .label {
      width: 60px;
      text-align: right;
      font-size: 14px;
    }
    .form-item .input {
      flex: 1;
    }
    .form-item input,
    .form-item select {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      width: 200px;
      height: 40px;
      box-sizing: border-box;
      padding: 10px;
      color: #666;
    }
    .form-item input::placeholder {
      color: #666;
    }
    .form-item .cancel,
    .form-item .submit {
      appearance: none;
      outline: none;
      border: 1px solid #ccc;
      border-radius: 4px;
      padding: 4px 10px;
      margin-right: 10px;
      font-size: 12px;
      background: #ccc;
    }
    .form-item .submit {
      border-color: #069;
      background: #069;
      color: #fff;
    }
  }
}
</style>